A new study wades into the ongoing debate over the health benefits of tofu, soy milk and other soy products. The study published in the journal Cancer looks at soy's effects on breast cancer survivors, in particular. NPR's Allison Aubrey takes a look.

ALLISON AUBREY, BYLINE: In the cafe line this morning at Everyman Espresso in Manhattan, manager Eric Grimm says orders like this one are pretty common.

UNIDENTIFIED MAN: Hey, what can I get you today?

UNIDENTIFIED PERSON: May I please have a soy latte to go?

AUBREY: About a third of his customers order soy milk or other plant-based creamers. It's a trend that is in part driven by what people think is healthy, but there's been some question about whether soy could be harmful to women with breast cancer. The concern has been that the estrogen-like compounds in soy might interfere with the effectiveness of breast cancer drugs like Tamoxifen. Now a new study of more than 6,000 women in the U.S. and Canada who had been diagnosed with breast cancer finds no downside to drinking that soy latte or eating other soy-based foods. Here's study author Feng Feng Zheng of Tufts University in Boston.

FENG FENG ZHENG: Our findings would suggest that soy food consumption does not have a harmful effect.

AUBREY: Research in Asian women has shown that soy can actually protect against breast cancer, so Zheng's says she was not surprised by the results of the study.

ZHENG: We found a 21 percent reduction in all causes of mortality among women with highest dietary intake compared to those with lowest intake.

AUBREY: But when she drilled down more deeply, it turned out that it was only women who had hormone-negative breast cancers who got the boost in longevity. For all the other women who had hormone-positive breast cancers, soy intake seemed to make no difference. Marian Neuhouser of the Fred Hutchinson Cancer Research Center in Seattle says this study is reassuring up to a point.

MARIAN NEUHOUSER: I think it provides a piece of the puzzle.

AUBREY: The soy consumption among the American and Canadian women in the study was actually pretty limited, she says.

ZHENG: Less than two milligrams a day. If you compare that to Asian populations that, on average, consume 40 to 50 milligrams a day, it's pretty low.

AUBREY: She says it's not clear what the results would be if women with breast cancer consumed more. For now, she says...

NEUHOUSER: Soy seems to be safe and may be beneficial for some women who have had a diagnosis of breast cancer...

AUBREY: ...At least given the current levels of consumption here and in Canada. Allison Aubrey, NPR News.

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